The present invention comprises a new and distinctive Lobelia plant, hereinafter referred to by the cultivar name Periwinkle Blue. This new cultivar was the result of a unique interspecific cross between Lobelia erinus and Lobelia valida. More specifically, the breeding program which resulted in the production of the new cultivar was carried out at Arroyo Grande, Calif. in 1997. The female or seed parent of Periwinkle Blue was the Lobelia erinus plant from the Palace Series named xe2x80x98Blue With Eyexe2x80x99 (unpatented) which exhibits dark purple-blue flowers with white centers or xe2x80x9ceyesxe2x80x9d and has a semi-trailing habit. The male or pollen parent of Periwinkle Blue was an unnamed Lobelia valida plant which exhibits lavender-blue flowers and an upright habit. The resulting seed was collected and germinated. From the flowering progeny, a single plant was selected and initially designated BPF-100, and now given the cultivar name xe2x80x98Periwinkle Bluexe2x80x99. The parentage of the new cultivar can be summarized as follows:
Lobelia erinusxc3x97Lobelia valida 
Asexual reproduction of the new cultivar by terminal cuttings taken during 1998 and 1999 at Arroyo Grande, Calif., U.S.A. has demonstrated that the characteristics of the new cultivar as herein described are firmly fixed and are retained through successive generations of such asexual propagation.
It was found that the cultivar of the present invention:
(a) exhibits initial upright growth followed by a semi-trailing habit,
(b) forms sky-blue flowers with white xe2x80x9ceyesxe2x80x9d,
(c) exhibits a vigorous growth habit,
(d) is extremely floriferous.
The xe2x80x98Periwinkle Bluexe2x80x99 cultivar has not been observed under all possible environmental conditions to date. Accordingly, it is possible that the phenotype may vary somewhat with variations in the environment, such as temperature, light intensity, and day length.
When the new cultivar of the present invention is compared to the Lobelia plant xe2x80x98Azuroxe2x80x99 (U.S. Plant Pat. No. 10,758) it is found that the new cultivar exhibits a more vigorous, trailing growth habit and lighter blue flower color.